Atomic Force Microscopy became a member of the Scanning Probe Microscopy family when it was introduced in 1985 by Gerard Binnig and Christof Gerber of the IBM Zurich Research Laboratory, along with Calvin F.Quate of Stanford University. Several other variations on surface scanning based on dragging a pointed probe across a surface. Thus in addition to offering nondestructive imaging at high resolution, AFM has the advatage of being able to image non-conducting materials.
AFM incorporates the use of a very small probe attached to the tip of a cantilever which is physically dragged across the surface of the sample. The tips are often fabricated from silicon nitride and come in a variety of shapes. Two of the most common tup shapes are conical and pyramidal, where the choice of tips to use depends upon the particular surface to be imaged, The tip geometry is important to the quality of the image taken, for example a tip that is not sharp will not scan edges very well since the side of the tip will hit a feature berfore the point of the tip does, thereby distorting the image of the feature. Scanning occours in a raster like pattern where the scanner scans a line in the x direction for example, and then returns to the beginning of that scan line. The scanner then moves a small amount in the y directin before scanning the next line in the x direction. A laser diode produces a light beam which is directed onto a cantilever to which the scanning probe is attached. The picture below shows the probe and the photodetector.
(a) path of laser onto the cantilever and to the photodetector (b) expanded view of the probe mount and cantilever
all of the above information is excerpted from Surface Study of Epitaxially Grown.Hightly Mismatched Semiconductor Materials Using Atomic Force Microscopy a Senior Honors Thesis by Ryan A Sherry
The above picture excerpted from Burleigh Instruments Personal SPM Quick Start Manual
page designed by Michelle Zeigler '00
last updated 7/9/97